Method for interleaving continuous length sequence

ABSTRACT

An interleaver provision method for providing a continuous length, an interleaving method, and a turbo-encoder thereof are disclosed. The interleaving method selects a basic interleaver having a proper length from among the basic interleaver set, which is predetermined to have the length represented by a multiple of the ARP fluctuation vector period. The interleaving method performs the dummy insertion and the pruning process to have the length acting as the basic-interleaver length, so that it can provide the ARP interleaver having a continuous length.

TECHNICAL FIELD

The present invention relates to a wireless communication technology,and more particularly to a method for providing an interleaversupporting a continuous length, an interleaving method, and aturbo-encoder thereof.

BACKGROUND ART

FIG. 1 is a block diagram illustrating a turbo-encoder.

If two recursive symmetric convolution (RSC) codes areparallel-concatenated by an interleaver, the turbo-code (TC) is formed.In more detail, turbo code can be formed by combining a parity bit (Y₁)generated by encoding an input data (X) of the turbo-encoder shown inFIG. 1 by a first RSC construction encoder (ENC₁) 101 and the otherparity bit (Y₂) generated by encoding the input data (X) by a second RSCconstruction encoder (ENC₂) 103.

The longer the minimum hamming distance (MHD), the higher the turbo-code(TC) performance. The MHD may be denoted by the number of bits havingdifferent information at neighboring positions among individualsequences.

Generally, if a sequence “000 . . . ” is used as a reference sequence,the MHD may be denoted by the number of bits different from thereference sequence. As a result, the MHD may be denoted by the number ofweights (i.e., the number of “1”) contained in individual sequences.Therefore, the MHD performance is affected by a specific action whichprevents the same information from being located at the neighboringpositions of sequences applied to the first and second RSC constructionencoders 101 and 103. This performance is under the control of theinterleaver 102.

FIG. 1 exemplarily shows an interleaver based on a regular rectangularpermutation. The interleaver of FIG. 1 applies an appropriatepermutation to a sequence of the length “k”, records the resultantsequence in a row direction of a rectangular matrix of M×N bits, andreads the recorded sequence in the column direction.

A detailed description of the interleaver shown in FIG. 1 is shown inFIG. 2.

FIG. 2 exemplarily shows a method for performing a regular permutation(RP).

The RP method of FIG. 2 writes a sequence in the row direction accordingto the above-mentioned regular rectangular permutation (RRP), reads thesequence in the column direction, and outputs the resultant sequence.For the convenience of description, the numbers written in the matrix inFIG. 2 are equal to the index (i) of the input sequence.

Generally, the relationship between the index of the input sequence inthe RP and the other index (j) of the output sequence can be representedby the following equation 1, so that the index (i) and the other index(j) can be mapped to each other by Equation 1:

i=Π(j)=P·j[mod K]  [Equation 1]

In Equation 1, “K” is the size of the interleaver. “P” and “K” aremutually-disjointed integers, and correspond to the numbers of columnsof FIG. 2. Based on the above-mentioned mapping relationship, FIG. 2shows the index mapping process executed by i=Π(j)=7·j[mod32] under K=32and P=7.

The input sequence (I) having the length of 32 bits is recorded in therow direction according to the above-mentioned index mappingrelationship, and is then read in the column direction, so that it ischanged to an output sequence (I′).

In the meantime, the RSC sequence may include a RTZ (Return-To-Zero)sequence which reduces the weight of a codeword. The RTZ sequenceenables the construction encoder to output a specific sequence in whichthe value “0” is repeated, so that the weight of the output sequence isdecreased.

In more detail, as shown in FIG. 1, provided that the input sequence ofthe first RSC construction encoder 101 is set to a sequence (I), and apredetermined RTZ sequence exists in the sequence (I), the weight of theparity bit (Y₁) created by the first RSC construction encoder 101becomes lower.

A sequence interleaved by the interleaver 102 is applied to the secondRSC construction encoder 103. if this sequence received in the secondRSC construction encoder 103 is called a sequence (I′), and theinterleaved sequence (I′) also includes the RTZ sequence, the weight ofthe parity bit (Y₂) created by the second RSC construction encoder 103becomes lower, so that the MHD of the whole codeword becomes lower.Therefore, the interleaver 102 must be designed not to generate the RTZsequence in the sequence (I′) received in the second RSC constructionencoder 103.

FIG. 3A shows an example of the RTZ (Return-To-Zero) sequence having theweight “2”. FIG. 3B shows an example of the RTZ (Return-To-Zero)sequence having the weight “3”. FIG. 3C shows an example of the RTZ(Return-To-Zero) sequence having the weights “6” and “9”.

In more detail, the RTZ sequence having the weight “2” is shown in FIG.3A. Referring to FIG. 3A, the input sequence (I) includes the RTZsequence in which the bit “1” is spaced apart from the other bit “1” bya predetermined distance corresponding to 7 bits. And, FIG. 3A shows theinterleaving based on the above-mentioned regular rectangularpermutation (RRP) in which the input sequence (I) is recorded in the rowdirection and is then read in the column direction.

In the case of the RTZ sequence having the weight “2” as shown in FIG.3A, the MHD (d_(min)) can be represented by the following equation 2:

d_(min)≅7M/2   [Equation 2]

In Equation 2, the number “7” is 7 bits indicating to the distancebetween two “1” values in the input sequence (I), M is the number ofrows in the M×N matrix, and the number “2” is the number of the values“1” indicating the last bits of individual sequences. As can be seenfrom FIG. 3A, the MHD (d_(min)) gets closer to “7M/2”.

FIG. 3B shows an example of the RTZ (Return-To-Zero) sequence having theweight “3”. In more detail, FIG. 3B shows an example of the RTZ(Return-To-Zero) sequence in which three “1” values (e.g., . . . 1101 .. . ) are arranged in the input sequence (I).

In the case of the RTZ sequence having the weight “3” as shown in FIG.3B, the MHD (d_(min)) can be represented by the following equation 3:

d_(min)≅3M/2   [Equation 3]

In Equation 3, the number “3” is 3 bits indicating to the distancebetween the last bits “1” in the input sequence (I), M is the number ofrows in the matrix, and the number “2” is the number of the values “1”indicating the last bits of individual sequences. As can be seen fromFIG. 3B, the MHD (d_(min)) gets closer to “3M/2”.

In the case of applying the regular permutation (RP) to the RTZ sequencein FIGS. 3A and 3B, the longer the length “K” of a total sequence, thehigher the value (d_(min)), thereby preventing the RTZ sequence frombeing contained in the output sequence (I).

In the meantime, FIG. 3C exemplarily shows the RTZ sequence having theweights “6” and “9”. In the case of this RTZ sequence of FIG. 3C, theMHD cannot be generally defined, and varies with a specific pattern ofthe corresponding sequence.

The input sequence (I) of FIG. 3C includes the RTZ sequence ( . . . 1101. . . ) in the input sequence arranged in the column direction, andincludes the other RTZ sequence ( . . . 100001 . . . ) in the outputsequence arranged in the row direction.

If the RTZ sequence is contained in the input sequence (I) having theweights “6” and “9” by the interleaving based on the RP, it can berecognized that the performance that the RTZ sequence is not containedin the output sequence (I) may be deteriorated.

Therefore, there has been widely used an almost regular permutation(ARP) causing the disorder while the RTZ sequence is read in the columndirection of the interleaver memory matrix. The ARP can maintain the RPcharacteristics having a good performance associated with the other RTZsequence of FIG. 3A or 3B, and can prevent the RTZ sequence of FIG. 3Cfrom being generated.

In brief, the ARP is acquired by adding fluctuation vectors to the RP.In more detail, the above-mentioned RP cannot avoid the RTZ sequencehaving the weight “6” or “9” in the interleaving process. In order toprevent the RTZ sequence having the weight “6” or “9” from beinggenerated in the interleaving process, the disorder must be encounteredin the RP, so that the above-mentioned fluctuation vectors are added tothe RP to encounter the disorder in the RP.

Presently, the ARP has been widely used as a turbo-code interleaver ofDVB-RCS, DVB-RCT, and IEEE 802.16. A variety of applications of theabove-mentioned ARP have been described in “ETSI EN 301 790v1.2.2(2000-12)” and “Draft IEEE standard Local and Metropolitan areanetworks, Part 16”.

FIG. 4 is a conceptual diagram illustrating the almost regularpermutation (ARP) based on the fluctuation vectors.

The ARP can be represented by the following index mapping relationshipof Equation 4, so that it can encounter the disorder in therecording/reading process by adding the fluctuation vectors to the RPusing the following Equation 4:

i=Π(j)=P·j+Q(j)mod K   [Equation 4]

In Equation 4, Q(j) is indicative of the fluctuation vector. And, thefluctuation vector Q(j) can also be represented by the followingequation 5:

Q(j)=A(j)·P+B(j)=C(α(j)·P+β(j))   [Equation 5]

In Equation 5, “C” is indicative of a disorder period, “A(j)” or “B(j)”is indicative of a periodic function having the period (C), and “P” isequal to or less than 20% of the value “K/P”. Also, “Q(0)” may be set to“0”, and the ARP can be defined by both “2(C-1)” number of integers(i.e., 2(C-1) integers) defining the values A(j) and B(j) and the value“P”.

FIG. 4 shows a variety of processes encountered while the sequence isrecorded or read by the above-mentioned fluctuation vector. Detaileddescription of the encountered processes has been disclosed in“Designing Good Permutations for Turbo-codes: Towards a Single Model”written by C. Berrou, and Y. Saouter et al.

In order to reduce the number of interleaver parameters defining theabove-mentioned ARP, a specific ARP capable of satisfying the followingconditions 1), 2), and 3) can be proposed as follows:

1) the ARP must apply a single value, which is set to any one of theremaining values other than “0”;

2) A(j)′ and B(j)′ exist in the ARP, in which each of A(j)′ and B(j)′ isa multiple of “C”; and

3) α(j) and β(j) are integers between “0” and “8”, and each of α(j) andβ(j) is set to a multiple of “C”.

A detailed application example of the above-mentioned ARP is as follows.

In more detail, the left part of FIG. 5 shows the index mappingrelationship based on the RP satisfying P=7 and K=32 in the same manneras in FIG. 2, and the right part of FIG. 5 shows that the mappingrelationship based on the above-mentioned RP is represented by thefluctuation vector Q(j) as shown in FIG. 6.

i=Π(j)=P·j+Q(j)mod K=7·j+Q(j)mod32   [Equation 6]

In Equation 6, Q(j) can be represented by the following Equation 7:

$\begin{matrix}\begin{matrix}{{Q(j)} = {C\left( {{{\alpha (j)} \cdot P} + {\beta (j)}} \right)}} \\{= \left\{ \begin{matrix}{{0,}\mspace{124mu}} & {{{if}\mspace{14mu} j} = {0\; {mod}\; 4}} \\{{{4 \cdot 1},}\mspace{101mu}} & {{{if}\mspace{14mu} j} = {1\; {mod}\; 4}} \\{{{4 \cdot 1 \cdot 7} + {4 \cdot 3}},} & {{{if}\mspace{14mu} j} = {2\; {mod}\; 4}} \\{{{4 \cdot 1 \cdot 7} + {4 \cdot 4}},} & {{{if}\mspace{14mu} j} = {3\; {mod}\; 4}}\end{matrix} \right.}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 7} \right\rbrack\end{matrix}$

In the case of the disorder encountered in a first-column directionalmapping process in the RP index mapping relationship shown in the leftside of FIG. 5, j=0 is mapped to i=0, j=1 is mapped to i=11 instead ofi=7, j=2 is mapped to i=22 instead of i=14, and j=3 is mapped to i=1instead of i=21, as shown in the right side of FIG. 5.

However, the above-mentioned fluctuation vector Q(j) is a functionhaving the period “C”, so that the interleaver size “K” (i.e., thelength “K” of the interleaving information) must be set to a multiple of“C”. In other words, the above-mentioned example in which the period Cis set to “4” can provide only the interleaver having the length denotedby a multiple of “4”, so that there is needed an improved technologycapable of providing the interleaver having a continuous lengthsimultaneously while using the ARP.

DISCLOSURE Technical Problem

Accordingly, the present invention is directed to a method forinterleaving a continuous-length sequence that substantially obviatesone or more problems due to limitations and disadvantages of the relatedart.

An object of the present invention is to provide a method forinterleaving a continuous-length sequence using an interleaver which caninterleave only a sequence having the length represented by a multipleof a specific-length value.

Another object of the present invention is to provide a method forproviding an interleaver which uses the ARP simultaneously while havingthe length not represented by a multiple of the fluctuation-vectorperiod “C”.

Still another object of the present invention is to provide a basicinterleaver concept, an interleaving method based on the pruningconcept, and a turbo-encoder including an interleaver capable ofperforming the basic interleaver concept and the pruning concept.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

Technical Solution

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, aninterleaving method comprising: inserting dummy information in an indexof an original sequence by a predetermined length corresponding to adifference in length between a basic interleaver selected from among abasic interleaver set and the original sequence; interleaving the dummyinformation inserted sequence having the length of the selected basicinterleaver using the selected basic interleaver; and outputting theinterleaved sequence corresponding to the index not having the dummyinformation from among indexes of the interleaved sequence, wherein theselected interleaver is selected from among at least one interleaverhaving a length represented by a multiple of a specific length, and thedummy information in the inserting the dummy information is inserted inan arbitrarily-selected position between the original sequences.

Preferably, the arbitrary-selected position in which the dummyinformation is inserted includes an initial position of the originalsequence.

Preferably, a the length of the selected basic interleaver is a minimumlength among lengths which are equal to or longer than the length of theoriginal sequence, and which are represented by the multiple of thespecific length.

Preferably, the method further comprises: mapping the index of theoutputted sequence according to the index of the original sequence,after the outputting the interleaved sequence.

Preferably, the basic interleaver set is pre-designed to have a lengthrepresented by a multiple of an ARP (Almost Regular Permutation)fluctuation-vector period.

Preferably, the specific length is equal to a length of the ARPfluctuation-vector period.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

Advantageous Effects

The present invention uses the interleaver having the lengthcorresponding to a multiple of a specific length, and at the same timeinterleaves the sequence having a continuous length.

Specifically, the present invention performs the pruning process on apredetermined basic interleaver having the length represented by amultiple of the period of the ARP fluctuation vector, so that it canprovide the ARP interleaver having a continuous length although thelength denoted by the above-mentioned fluctuation-vector period has notbeen established.

Also, the present invention provides the basic interleaver concept, theinterleaving method based on the pruning concept, and the turbo-encoderequipped with the interleaver executing the interleaving method, so thatit can perform the ARP having a continuous length without generatingadditional overheads.

DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention, illustrate embodiments of the inventionand together with the description serve to explain the principle of theinvention.

In the drawings:

FIG. 1 is a basic block diagram illustrating a turbo-encoder;

FIG. 2 is a conceptual diagram illustrating a method for performing aregular permutation (RP);

FIG. 2 exemplarily shows a method for performing a regular permutation(RP);

FIG. 3A shows an example of the RTZ (Return-To-Zero) sequence having theweight “2”, FIG. 3B shows an example of the RTZ (Return-To-Zero)sequence having the weight “3”, and FIG. 3C shows an example of the RTZ(Return-To-Zero) sequence having the weight “6” or “9”;

FIG. 4 is a conceptual diagram illustrating the almost regularpermutation (ARP) based on the fluctuation vectors according to thepresent invention;

FIG. 5 exemplarily shows a method for performing the ARP of FIG. 4according to the present invention;

FIG. 6 is a flow chart illustrating a method for providing aninterleaver having a continuous length using the basic interleaverconcept according to the present invention;

FIG. 7 is a flow chart illustrating an interleaving method according toone embodiment of the present invention;

FIG. 8 is a flow chart illustrating an interleaving method according toanother embodiment of the present invention; and

FIG. 9 is a block diagram illustrating a turbo-encoder including theinterleaver according to the present invention.

BEST MODE

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

Prior to describing the present invention, it should be noted that mostterms disclosed in the present invention correspond to general termswell known in the art, but some terms have been selected by theapplicant as necessary and will hereinafter be disclosed in thefollowing description of the present invention. Therefore, it ispreferable that the terms defined by the applicant be understood on thebasis of their meanings in the present invention.

For the convenience of description and better understanding of thepresent invention, general structures and devices well known in the artwill be omitted or be denoted by a block diagram or a flow chart.Wherever possible, the same reference numbers will be used throughoutthe drawings to refer to the same or like parts.

The present invention provides the basic interleaver concept to solvethe problems of the conventional art, incapable of providing theinterleaver having a continuous length due to the ARP having a specificperiod.

However, the following interleaving method based on the basicinterleaver according to the present invention is not limited to onlythe above-mentioned ARP examples, and can also be applied to a varietyof conventional interleaving schemes, each of which not only interleavesusing the ARP but also interleaves the sequence having a lengthrepresented by a multiple of a specific length.

In this case, the basic interleaver has a predetermined length decidedto implement a desired interleaver having a required length. Generally,the basic interleaver sets having various lengths may be prescribed ifrequired.

FIG. 6 is a flow chart illustrating a method for providing aninterleaver having a continuous length using the basic interleaverconcept according to the present invention.

The interleaving method of FIG. 6 selects an interleaver having thelength (K′) from among basic interleaver sets to provide the interleaverhaving the length (K) at step-S601.

In this case, K′ is a multiple of the fluctuation-vector period (C) forimplementing the ARP using the concept of FIG. 5, and it is preferablethat the basic interleaver having the minimum length K′ satisfying K≦K′is selected to facilitate the next pruning process.

Thereafter, if K≦K′, the basic interleaver having the length K′ selectedat step S601 can be adjusted by the interleaver having the length K.This interleaver-length adjustment for each interleaving step willhereinafter be described in detail.

(K′-K) dummy information pieces are inserted in the input sequence ofthe interleaver at step S602. If the input sequence is B=(b₀, b₁, . . ., b_(k−1)), (K-K′) number of dummy bits are inserted in the inputsequence B, so that another sequence B′=(b′₀, b′₁, . . . , b_(k−1),b_(k), b_(k+1), . . . , b_(k′−1)) is formed.

According to the aforementioned embodiment of the present invention, theposition at which dummy information is inserted in the input sequence isset to the part having an index higher than “K”. However, according toanother embodiment of the present invention, the aforementioned positionmay be set to another part, and a detailed description thereof willhereinafter be described.

In this way, the dummy information inserted input sequence is adjustedto be the length K′, so that the ARP interleaving based on the basicinterleaver having the length K′ can be conducted at step S603.

If the output sequence which has been ARP-interleaving-completed at stepS603 is set to “0”, this output sequence can be represented by O=(o₀,o₁, . . . , o_(k′−1)).

Thereafter, a non-dummy index other than the output-sequence indexcorresponding to the input-sequence index in which the dummy informationis inserted is outputted at step S604.

In more detail, if the relationship between the input-sequence index (i)and the output-sequence index (j) is represented by i=Π(j) at step S603,this indicates that the above-mentioned example outputs the index otherthan the output index (j) corresponding to i=k, k+1, . . . , k′−1.Therefore, only information stored in the position not having the dummyinformation remains in the output sequence (0′).

And, although the above-mentioned embodiment has been disclosed on thebasis of a first method for outputting data other than the indexequipped with the dummy information, a second method for removinginformation of the corresponding index from the output sequenceaccording to the relationship o_(j)=b_(i=Π(j)) can also acquire the sameresult as the first method.

A detailed example of the interleaving method according to theabove-mentioned embodiment will hereinafter be described.

FIG. 7 is a flow chart illustrating an interleaving method according toone embodiment of the present invention.

The interleaving method of FIG. 7 inserts the dummy information in aterminal of the input sequence, so that it outputs an index other thanan index located at the position at which the dummy bit is inserted inthe output sequence having been interleaved.

Firstly, the index (i) of the input sequence is initialized to “0” atstep S701. Then, the interleaving method of FIG. 7 determines whetherthe value (i) is equal to or higher than “K” at step S702. If the value(i) is less than “K” at step S702, the interleaving method goes to stepS703, so that it matches each information of the input sequence B toeach information of the other sequence B′ in which the dummy bit isinserted at step S703.

However, if the value (i) is equal to or higher than “K”, theinterleaving method goes to step S704, so that it inserts the dummy bitin the terminal position of the sequence B′ at step S704.

In the meantime, the index (i) of the input sequence sequentiallyincreases at step S705. If the value (i) is less than K′, theinterleaving method returns to step S702, so that the above-mentionedoperations are repeated. For example, if K′=16 and K=14, a dummy valueis inserted in each of the value b₁₄ of i=14 and the other value b₁₅ ofi=15.

In the meantime, if the value (i) is equal to or higher than K′ at stepS706, the interleaving method goes to step S707, so that the ARPinterleaving is conducted at step S707. If K′=16 and K=14, the indexmapping relationship equation of the ARP interleaving and thefluctuation vector Q(j) can be represented by the following Equation 8:

i=Π(j)=7·j+Q(j)mod 16   [Equation 8]

In Equation 8, the fluctuation vector Q(j) can be represented by thefollowing equation 9:

$\begin{matrix}\begin{matrix}{{Q(j)} = {C\left( {{{\alpha (j)} \cdot P} + {\beta (j)}} \right)}} \\{= \left\{ \begin{matrix}{{{4 \cdot \left( {{0 \cdot 7} + 0} \right)},}\mspace{20mu}} & {{{if}\mspace{14mu} j} = {0\; {mod}\; 4}} \\{{{4 \cdot \left( {{1 \cdot 7} + 1} \right)},}\mspace{20mu}} & {{{if}\mspace{14mu} j} = {1\; {mod}\; 4}} \\{{{4 \cdot \left( {{1 \cdot 7} + 3} \right)},}\mspace{20mu}} & {{{if}\mspace{14mu} j} = {2\; {mod}\; 4}} \\{{{4 \cdot \left( {{1 \cdot 7} + 5} \right)},}\mspace{20mu}} & {{{if}\mspace{14mu} j} = {3\; {mod}\; 4}}\end{matrix} \right.}\end{matrix} & \left\lbrack {{Equation}\mspace{14mu} 9} \right\rbrack\end{matrix}$

Therefore, the sequence generated by the ARP interleaving of Equations 8and 9 can be represented by Π_(k′)={0, 7, 6, 5, 12, 3, 2, 1, 8, 15, 14,13, 4, 11, 10, 9}.

For the convenience of description, it is considered that individualnumbers contained in the aforementioned output sequence indicate indexesof the input sequence. Thereafter, the interleaving method outputs theindexes other than a specific index (j) matched to the index i>K−1 usingthe relationship Π(j)=i.

In more detail, the sequence generated by the ARP interleaving may berepresented by Π_(k)={0, 7, 6, 5, 12, 3, 2, 1, 8, 13, 4, 11, 10, 9}having the length K at step S708, and this means that the remainingindexes other than the index (j) corresponding to i=14 and i=15 havebeen outputted.

Although the above-mentioned embodiment has disclosed that the dummyinformation is inserted in the terminal of the input sequence, it shouldbe noted that the insertion position of the dummy information is notalways limited to the terminal of the input sequence.

The interleaving method according to another embodiment inserts dummyinformation in (K′-K) indexes located between the input sequences, sothat it can conduct the ARP interleaving. In this case, it is assumedthat the insertion position of the dummy information includes theinitial position of the input sequence. And, the above-mentionedinterleaving method according to another embodiment can also includeanother example in which all of (K′-K) dummy information pieces areinserted in the initial position of the input sequence.

The interleaving method according to the above-mentioned embodimentselects (K′-K) indexes from among input sequence indexes between “0” and“K′−1”, and inserts the dummy information in the selected (K′-K) indexesat step S602. The interleaving method outputs an index not havingoutput-sequence index corresponding to the index in which the dummyinformation has been inserted using the relationship of i=Π(j). So,since the index is removed from the input sequence, the output sequencemay further perform mapping the output-sequence index to be suitable foran original-length index.

A detailed description of the above-mentioned embodiment willhereinafter be described with reference to FIG. 8. FIG. 8 is a flowchart illustrating an interleaving method according to anotherembodiment of the present invention.

Referring to FIG. 8, (K′-K) indexes are selected from among theinput-sequence index (i) between “0” and “K′−1” at step S801, and thedummy information is inserted in a corresponding index at step S802.

In more detail, if K′=16 and K=14, the information of i=4 and 10 (where0≦i≦15) is selected as the dummy-information insertion index. Then, theARP interleaving of Equations 8 and 9 is conducted at step S803, so thatthe sequence having the length K′ can be represented by Π_(k′)={0, 7, 6,5, 12, 3, 2, 1, 8, 15, 14, 13, 4, 11, 10, 9}.

The interleaving method of FIG. 8 outputs the remaining indexes otherthan an input-sequence index in which the dummy information is inserted,from among the sequence having the length K′ at step S804.

For example, if the dummy information is represented by o₁₂=i₄ ando₁₄=i₁₀, the interleaving method outputs only the remaining indexesother than the corresponding index from among the index (j) of theoutput sequence. Therefore, the output sequence having the length K′ isrepresented by Π_(pre-mapping k)={0, 7, 6, 5, 12, 3, 2, 1, 8, 15, 14,13, 11, 9}. However, it should be noted that the mutual index adjustmentbetween the aforementioned output sequence having the length K′ and theother sequence having the length K is needed. For example, theabove-mentioned sequence having the length K′ may include the indexes 14and 15 not contained in the input sequence having the length K.

Therefore, the interleaving method of FIG. 8 further includes the stepof mapping the index to be suitable for the original input-sequenceindex at step S805.

As can be seen from the above-mentioned example, the index “5” of theinput sequence is mapped to “4”, the index “6” of the input sequence ismapped to “5”, the index “8” of the input sequence is mapped to “7”, theindex “9” of the input sequence is mapped to “8”, the index “11” of theinput sequence is mapped to “9”, the index “12” of the input sequence ismapped to “10”, the index “13” of the input sequence is mapped to “11”,the index “14” of the input sequence is mapped to “12”, and the index“15” of the input sequence is mapped to “13”. As a result, the outputsequence having the final length K can be represented by Π_(k)={0, 6, 5,4, 10, 3, 2, 1, 7, 13, 12, 11, 9, 8}.

Preferably, according to the above-mentioned embodiment, theinterleaving method may insert all of the dummy information in theinitial position of the input sequence. In more detail, if K′=16 andK=14, two dummy information pieces are inserted into the initialposition (i.e., i=0 and 1) of the input sequence. Thereafter, the ARPinterleaving based on Equations 8 and 9 is conducted at step S803, sothat the interleaving method outputs the sequence having the length K′.

The remaining indexes other than the input-sequence index including thedummy information from among the sequence having the length K′ may begenerated.

However, it should be noted that the index adjustment among theaforementioned index and the other input sequence having the length K isrequired. Therefore, the interleaving method may further include thestep of mapping the index to be suitable for an index of the originalinput sequence. Therefore, the output sequence of the final length K maybe represented by Π_(k)={5, 4, 3, 10, 1, 0, 6, 13, 12, 11, 2, 9, 8, 7}.

According to the above-mentioned embodiment in which the dummyinformation is inserted in the initial position of the input sequence,considering the aforementioned function in which the other redundantbits inserted in the rate matching process are inserted in the frontpart of the sequence, the above-mentioned interleaving method has anadvantage in that the next original sequence can be easily recovered.

Device characteristics of the turbo-encoder including the interleavingcapable of performing the interleaving providing a continuous lengthwill hereinafter be described.

FIG. 9 is a block diagram illustrating a turbo-encoder including theinterleaver according to the present invention.

Referring to FIG. 9, the turbo-encoder includes a first constructionencoder 901, a second construction encoder 902, and an interleaver 903.

Differently from FIG. 1, the interleaver 903 of FIG. 9 includes an ARPinterleaver 906, a basic-interleaver selection module 904, a dummyinsertion module 905, an index mapping module (also called an indexmapper) 907. The basic-interleaver selection module 904 selects thebasic interleaver having a proper length from among the basicinterleaver sets. The dummy insertion module 905 selects an index inwhich the dummy information is to be inserted, and inserts the dummyinformation in the selected index. The index mapping module (also calledan index mapper) 907 outputs the remaining indexes other than the indexequipped with the dummy information, and performs the index mapping ifrequired.

By the above-mentioned components of the interleaver 903, the lengthsequence instead of the fluctuation-vector period can be ARP-interleavedby the dummy insertion and the removing of the index including thedummy.

In this way, if the length-adjusting modules (e.g., thebasic-interleaver selection module 904, the dummy insertion module 905,and the index-removing module 907) are contained in the interleaver 903,the length of each sequence applied to the first and second encoders 901and 902 has the completed-sequence length having no dummy information.So, even the dummy information is encoded by the first and secondencoders 901 and 902, and the parity bit is generated to preventadditional overhead from being generated.

It should be noted that most terminology disclosed in the presentinvention is defined in consideration of functions of the presentinvention, and can be differently determined according to intention ofthose skilled in the art or usual practices. Therefore, it is preferablethat the above-mentioned terminology be understood on the basis of allcontents disclosed in the present invention.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

INDUSTRIAL APPLICABILITY

As apparent from the above description, the interleaving methodaccording to the present invention can be applied to not only the ARPinterleaver but also a predetermined interleaving method having thelength denoted by a multiple of a specific length.

The interleaving method uses the interleaver having the lengthcorresponding to a multiple of a specific length, and at the same timeinterleaves the sequence having a continuous length.

Specifically, the interleaving method performs the pruning process on apredetermined basic interleaver having the length represented by amultiple of the period of the ARP fluctuation vector, so that it canprovide the ARP interleaver having a continuous length although thelength denoted by the above-mentioned fluctuation-vector period has notbeen established.

And, the present invention provides the basic interleaver concept, theinterleaving method based on the pruning concept, and the turbo-encoderequipped with the interleaver executing the interleaving method, so thatit can perform the ARP having a continuous length without generatingadditional overheads.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. An interleaving method comprising: inserting dummy information in anindex of an original sequence by a predetermined length corresponding toa difference in length between a basic interleaver selected from among abasic interleaver set and the original sequence; interleaving the dummyinformation inserted sequence having the length of the selected basicinterleaver using the selected basic interleaver; and outputting theinterleaved sequence corresponding to the index not having the dummyinformation from among indexes of the interleaved sequence, wherein theselected interleaver is selected from among at least one interleaverhaving a length represented by a multiple of a specific length, and thedummy information in the inserting the dummy information is inserted inan arbitrarily-selected position between the original sequences.
 2. Themethod according to claim 1, wherein the arbitrarily-selected positionin which the dummy information is inserted includes an initial positionof the original sequence.
 3. The method according to claim 1, wherein:the length of the selected basic interleaver is a minimum length amonglengths which are equal to or longer than the length of the originalsequence, and which are represented by the multiple of the specificlength.
 4. The method according to claim 1, further comprising: mappingthe index of the outputted sequence according to the index of theoriginal sequence, after the outputting the interleaved sequence.
 5. Themethod according to claim 1, wherein the basic interleaver set ispre-designed to have a length represented by a multiple of an ARP(Almost Regular Permutation) fluctuation-vector period.
 6. The methodaccording to claim 5, wherein the specific length is equal to a lengthof the ARP fluctuation-vector period.